The present invention generally relates to testing of intelligent electronic devices of a power system, and more specifically, to a handheld communication tester and method for testing direct serial communication capability of an intelligent electronic device in a power system.
Electric utility systems or power systems are designed to generate, transmit and distribute electrical energy to loads. In order to accomplish this, power systems generally include a variety of power system elements such as electrical generators, electrical motors, power transformers, power transmission lines, buses and capacitors, to name a few. As a result, power systems also include a variety of intelligent electronic devices (IEDs) for protecting, monitoring, controlling, metering and/or automating power system elements. For example, one type of IED, a microprocessor- or FPGA-based modern protective relay, is configured to protect the power system elements from abnormal conditions such as electrical short circuits, overloads, frequency excursions, voltage fluctuations, and the like. Another type of IED, a microprocessor- or FPGA-based meter is used for tracking system power delivery and consumption.
In addition to power system elements and IEDs, power systems also include communication schemes that enable IED-to-IED communication as well as IED-to-computer communication, and the like. For example, U.S. Pat. No. 5,793,750, entitled “System of Communicating Output Function Status Indications Between Two or More Power System Protective Relays,” discloses a communication system where each of two microprocessor- or FPGA-based modern protective relays included both transmit and receive modules adapted to enable direct transmission of output status bits to the other protective relay. Such output status bits result from relay processing of measured voltages and/or currents on, for example, a monitored transmission line. As a result, output status bits transmitted from a first protective relay are “mirrored” in the second protective relay and then used by the second protective relay to make operational decisions. Thus, unlike slower prior transmission methods that required the use of separate communication modules as intermediaries, the communication system of the '750 patent facilitates speedy transmission and therefore quick identification of the existence and location of a fault on the transmission line monitored by the two protective relays.
An improvement to the '750 patent, U.S. Patent, Publication No. 2003/0007514, entitled “Relay-to-Relay Direct Communication System in an Electric Power System,” the contents of which are hereby incorporated by reference, discloses a communication system between at least two protective relays that enables direct transmission of not only output status bits, but also digitized analog values (e.g., metering information, breaker wear information, security enhancement information) and digitized virtual terminal data (i.e., data transmitted via a communication link established between a user located at a port of a first relay and a second relay). Accordingly, communication link usage between the two protective relays is optimized because otherwise vacant channels can be used to transmit synchronized successive data messages that include the output status bits, the digitized analog values and virtual terminal data. Further, synchronized transmission of successive data messages facilitates rapid transmission of multi-bit digitized analog values and virtual terminal data between a first and a second protective relay.
In both the '750 patent and the 2003/0007514 patent application publication, the first and second protective relays or other IEDs are operatively connected to each other via a serial communication link to enable the bi-directional “mirrored bits communication”. The serial communication link may be configured as an RF link, a microwave link, an audio link, a fiber optic link, or another other type of suitable link adapted to carry serialized data.
When installed in a power system, operational testing of the coupled IEDs (e.g., protective relays) and their associated serial communication link is conducted to ensure, inter alia, mirrored bit communication capability. A Mirrored Bits® Interface device is typically used to test mirrored bit communication capability for both the transmit and the receive function of an IED. The Mirrored Bits® Interface device includes a number of operator actuated pushbuttons and two sets of an equal number (e.g., eight) of light emitting diodes (LEDs) in order to enable the testing.
While effective for testing the mirrored bit communication capability of an IED, the size of the Mirrored Bits® Interface device makes it cumbersome in some applications such as field testing. In addition, the user must hand-enter the Baud rate, the receive identification number (RX ID) and the transmit identification number (TX ID) of the tested IED into the Mirrored Bits® Interface device prior to testing mirrored bit communication capability of the IED; a time-consuming and error prone process.